METHODS AND SYSTEMS FOR EXTENDING THE RANGE FOR FIBER OPTIC DISTRIBUTED TEMPERATURE (DTS) SYSTEMS

• US 20110280277A1
• Filed: 01/17/2009
• Published: 11/17/2011
• Est. Priority Date: 01/18/2008
• Status: Active Grant

• Current Assignee: Sensortran Incorporated (Halliburton Company)
• Original Assignee: Sensortran Incorporated (Halliburton Company)
• Inventors: Kent, Kalar, Ajgaonkar, Mahesh, Chung, Lee, Sanders, Michael
• Granted Patent: US 8,333,505 B2
• Time in Patent Office: Days
• US Class Current: 374/137
• CPC Class Codes: G01K 11/32 using changes in transmittance, scattering or luminescence in optical fibres

Abstract

Systems and methods for extending the range of a fiber optic DTS system are provided. In one respect, a method may provide steps for transmitting, in a first time period, an optical signal at a first energy level through an optical fiber, collecting backscatter signals as a result of the first transmission, adjusting the first energy level to a second energy level, transmitting, in an additional time period, the adjusted optical signal through the optical fiber, collecting backscatter signals as a result of the adjusted transmissions, and using a portion of the collected backscatter as a result of the first transmission and a portion of the collected backscatter as a result of the additional transmissions, determining one or more parameter profiles, such as a temperature profile.

Claims

1. A method for extending the distance range of a fiber optic distributed temperature system comprising the steps of:

a. transmitting, in a first time period, a first optical signal at a first energy level through an optical fiber;

b. collecting backscatter signals as a result of said first transmission;

c. transmitting, in at least one additional time period, an additional optical signal at an additional energy level through said optical fiber;

d. collecting backscatter signals as a result of said additional transmissions; and

e. using a portion of the collected backscatter as a result of said first transmission and a portion of the collected backscatter as a result of said additional transmissions, determining one or more parameter profiles.

2. The method for extending the distance range of a fiber optic distributed temperature system of claim 1, wherein said first transmission of said first optical signal corresponds to a first length of said optical fiber and said additional transmissions of said additional optical signal corresponds to additional lengths of said optical fiber.

3. The method for extending the distance range of a fiber optic distributed temperature system of claim 1, where each said optical signal energy level is adjusted to be greater than the energy level of the optical signal preceding it.

4. The method for extending the distance range of a fiber optic distributed temperature system of claim 3, wherein adjusting each level to a greater energy level comprises adjusting a variable optical attenuator.

5. The method for extending the distance range of a fiber optic distributed temperature system of claim 3, wherein adjusting each level to a greater energy level comprises adjusting the optical source'"'"'s transmitting energy by changing the operating condition of the optical source

6. The method for extending the distance range of a fiber optic distributed temperature system of claim 1, wherein using a portion of the collected backscatter as a result of the first transmission and a portion of the collected backscatter as a result of each additional transmission comprises combining a portion of the collected backscatter signals as a result of the first transmission and a portion of the collected backscatter signals as a result of each additional transmission.

7. The method for extending the distance range of a fiber optic distributed temperature system of claim 1, wherein the one or more parameter profiles comprise a temperature profile.

8. A system for extending the distance range of a fiber optic distributed temperature system comprising:

a. an optical source;

b. an optical fiber;

c. a variable optical attenuator; and

d. a processor coupled to the variable optical attenuator, wherein the processor is configured to;

i. adjust, in a first time period, said variable optical attenuator to result in a first transmission from said optical source through said optical fiber with a first optical energy level;

ii. collect backscatter signals corresponding to said first transmission;

iii. adjust, in at least one additional time period, the variable optical attenuator to result in an additional transmission from the optical source through the optical fiber with an additional optical energy level;

iv. collect backscatter signals corresponding to each additional transmission; and

v. determine a parameter profile based at least on the collected backscatter signals corresponding to the first and additional transmissions.

9. The system for extending the distance range of a fiber optic distributed temperature system of claim 8, wherein said optical source is a constant power optical source.

10. The system for extending the distance range of a fiber optic distributed temperature system of claim 8, wherein the processor is configured to collect Stokes and anti-Stokes bands corresponding to the first transmission and Stokes and anti-Stokes bands corresponding to each additional transmission.

11. The system for extending the distance range of a fiber optic distributed temperature system of claim 8, wherein the processor is configured to determine the temperature profile based at least on a portion of the collected backscatter signals corresponding to said first and additional transmissions.

12. The system for extending the distance range of a fiber optic distributed temperature system of claim 8, wherein the processor is configured to add a portion of the collected backscatter signals corresponding to said first transmission to a portion of the collected backscatter signals corresponding each additional transmission.